A spin-crossover framework endowed with pore-adjustable behavior by slow structural dynamics

Host-guest interactions play critical roles in achieving switchable structures and functionalities in porous materials, but design and control remain challenging. Here, we report a two-dimensional porous magnetic compound, [FeII(prentrz)2PdII(CN)4] (prentrz = (1E,2E)−3-phenyl-N-(4H-1,2,4-triazol-4-yl)prop-2-en-1-imine), which exhibits an atypical pore transformation that directly entangles with a spin state transition in response to water adsorption. In this material, the adsorption-induced, non-uniform pedal motion of the axial prentrz ligands and the crumpling/unfolding of the layer structure actuate a reversible narrow quasi-discrete pore (nqp) to large channel-type pore (lcp) change that leads to a pore rearrangement associated with simultaneous pore opening and closing. The unusual pore transformation results in programmable adsorption in which the lcp structure type must be achieved first by the long-time exposure of the nqp structure type in a steam-saturated atmosphere to accomplish the gate-opening adsorption. The structural transformation is accompanied by a variation in the spin-crossover (SCO) property of FeII, i.e., two-step SCO with a large plateau for the lcp phase and two-step SCO with no plateau for the nqp phase. The unusual adsorption-induced pore rearrangement and the related SCO property offer a way to design and control the pore structure and physical properties of dynamic frameworks.


Reviewer #1 (Remarks to the Author):
The authors describe a gate-opening adsorption in the Hofmann-type framework, which demonstrates water-induced variations of spin crossover. This is interesting on its own, but was previously presented for a Hofmann-type framework by Real et al. (Chem. Sci. 2020, 11, 11224-11234;reference 40). Moreover, authors postulate presence of the "phase-coexistence state of individual crystals". Such an observation would be very valuable, but in my opinion authors do not present sufficient scientific evidence to support this claim. The design of the appropriate experiment is challenging, but it seems clear that it would require use of space-resolved techniques, while the authors performed most of the characterization on bulk powder samples (in addition to the reference 47, I encourage the authors to read the article by Neimark et al. in J. Phys. Chem. Lett. 2011, 2, 2033-2037. Moreover, manuscript contains numerous technical drawbacks that must be resolved before publication: 1) Single-crystal X-ray diffraction data for 1-lcp phase lead to structure solutions that show very large residual electron density in the proximity of the palladium ion. Authors use hundreds of OMIT instructions (more than 700 in case of 1-lcp at 150K) in order to artificially remove this electron density, which is a case of data manipulation that should never be performed. Instead, an adequate twin law should be applied to systematically remove electron density attributed to the twinned crystal or the experiment itself should be repeated (comments 3 and 5).
2) Crystal structure 1-nqp at 250 K is characterized by R1 > 0.15 and data completeness below 73%. In the CIF file authors claim: "The final refinement results with low R1: 0.1537/I > 2σ (I) […] are undoubted." This statement is definitely false, as R1 above 0.1 already renders the structure unreliable. Moreover, CHECKCIF clearly recognizes crystal twinning, which should be treated systematically, instead of data removal. 3) Page 4, lines 69-70: "Crystals of the lcp phase (1-lcp) were obtained by stabilizing the as-grown crystals in air for 3 h". What is the reason for this 3-hour long stabilization period? This may result in partial exchange of crystallization solvent (compound crystallizes from MeOH/H2O mixture) and/or crystallization solvent loss. Both factors may contribute to the bad quality of single-crystal X-ray diffraction data for 1-lcp. The authors should repeat diffraction experiments for the crystal as-grown from the reaction mixture. 4) Page 5, line 80: "The crystals of the nqp phase 1·4/3H2O were obtained by heating 1·9/2H2O to 433 K for 48 h under vacuum". Very long heating at 433 K may lead to crystal decomposition, as evidenced by PXRD pattern of 1 after heating at 433 K for 48h under vacuum ( Figure 4 in the SI), which shows very large peak broadening and low signal/noise ratio. Therefore it is mandatory to perform TGA experiment at low heating rate (<1 K/min) for 1·9/2H2O, in order to determine the lowest possible temperature that will facilitate water loss. Authors seem to have access to the necessary equipment, as they have demonstrated TGA results in their previous papers (for example Inorg. Chem. 2021, 60, 7337-7344). 5) Page 5, lines 80-81 and lines 92-93: "The crystals of the nqp phase 1·4/3H2O were obtained by heating 1·9/2H2O to 433 K for 48 h under vacuum and cooling in air" and "Notably, an attempt to obtain the crystal structure of completely dehydrated crystal of 1 failed because it was instantly converted to 1·4/3H2O". Cooling in humid air may result in partial rehydration, but in spite of that authors should characterize crystal structure of anhydrous 1. This should be achieved by gentle heating of 1·9/2H2O in dry nitrogen stream in situ before the single-crystal diffraction measurement (the exact conditions may be deduced from TGA). 6) Water adsorption isotherm depicted in the Figure 2A may be influenced by partial sample decomposition, resulting from very long activation at high temperature (please compare with Figure 4 in the SI). The identity of the sample should be re-tested by PXRD measurement after water sorption experiment. 7) 1·4/3H2O line in the Figure 2C actually corresponds to 5/3H2O level, which is misleading to the reader and should be corrected. Moreover the "Uptake" drops down to -0.2 mol/mol for 1200 min., which may be another sign of partial sample decomposition at 450 K and undermines validity of this plot. 8) Authors provide long discussion of PXRD results in the attempt to prove the phase-coexistence in the single crystal. I need to emphasize that it is impossible to draw conclusions about single crystal on the basis of powder measurements. There are many factors that may be responsible for observed changes in PXRD pattern, phase-coexistence within single crystal is not necessarily one of them. 9) Page 7, lines 148-150: "the phase-coexistence state works on individual crystals rather than a physical mixture of two pure phases because the PXRD patterns of a physical mixture of the lcp phase 1·9/2H2O and nqp phase 1·4/3H2O did not show any significant change after spraying the water mist Supplementary Fig. 14)". This conclusion is in contradiction to the water adsorption isotherm ( Figure 2B) which clearly shows that nqp-to-lcp transition appears above p/p0 = 0.8. Lack of significant changes in the PXRD may simply result from limited vapor diffusion or too short stabilization time. 10) Page 7, lines 155-157: "the phase-coexistence state of individual crystal is directly supported by single-crystal diffraction analysis, the crystal lattices of both nqp and lcp phases can be indexed in reciprocal space from the data collected on a partially desolvated single crystal at 310 K". It is not unusual to observe overlapping diffraction patterns in a single-crystal diffraction experiment. This may result from crystal breaking, twinning (which is most probably the case, as it is easily recognized by CHECKCIF in crystal structures of 1-nqp and 1-lcp) and other factors. It would require spatiallyresolved diffraction with use of highly focused beam in order to prove phase-coexistence in the single crystal in a diffraction experiment (please see SI in J. Am. Chem. Soc. 2015, 137, 15390-15393 or Cryst. Eng. Comm. 2018, 20, 2233-2236 for similar experiments on welded crystals, where macroscopic domains were identified). 11) Magnetic measurements seem to contradict the hypothesis of phase-coexistence in single crystals of 1. Figures 3B-D look like linear combinations of curves presented in Figure 3A and Figure  3E/3F. This would be highly unexpected for the phase-coexistence within single crystal, as SCO in this system is highly cooperative. Moreover, small changes in water content may very strongly influence SCO behavior, even in the absence of phase-coexistence phenomenon (well depicted by Song et al. in Dalton Trans. 2016, 45, 18643-18652). 12) Sample preparation for magnetic measurements should be described in details in the discussion of magnetic properties (exact conditions of sample stabilization that lead in preparation of each phase mixture). 13) Methods section should contain description of the measurement setup (for HTK 1200N and TTK450) as well as sample preparation for PXRD measurements. Type of the sample holder and sample thickness are critical for assessing efficiency of vapor diffusion in such experiments. 14) Methods section should contain detailed description of sample packing for magnetic measurements. How was the sample stability achieved?
There are also several minor issues that should be corrected: 1) Page 2, line 16: "…leads to a pore rearrangement associated with local negative adsorption". No negative adsorption is observed for the presented network and therefore this part of the sentence is an unnecessary exaggeration. The observed behavior is pore rearrangement only and the new term "local negative adsorption" should not be coined.
2) The first paragraph of the introduction section is not clear and especially lines 30-40 need rephrasing. 3) Page 3, line 31: "extend-retract motion12-14". References 12-14 are not a good demonstration of this term. 4) Page 4, line 75: "3D porous structure with channel pores (15.027 × 6.554 Å2)". Even assuming that atoms are dimensionless, the pore dimensions would be 14.3 Å (for Pt-Pt) x 5.3 Å (for H-H of neighboring organic ligands). The authors should clearly specify which distances were listed as "channel pores" dimensions. 5) On numerous occasions distances in the crystal structure are mentioned without uncertainty of their determination, which should be corrected. 6) CHECKCIF report for 1-nqp at 100K contains the following alert: PLAT920_ALERT_1_B Theta(Max) in CIF and FCF Differ by ........... 2.68 Degree. Please clarify what is the reason for that. 7) Kepert et al. reported Hofmann-type frameworks based on very similar ligands and showing almost identical topology as 1-nqp (Chem. Sci. 2018, 9, 5623-5629 and Dalton Trans. 2021, 50, 1434-1442 -those references should be mentioned in the introduction. (i) The microanalyses of the two phases are good. However, a straightforward check would be to run thermogravimetric analyses (TGAs) on the two phases, as an extra confirmation of their water content. I was surprised those weren't included in the SI, and they should be added to the revision.
(ii) The crystal structures of the 1.nqp phase are of low quality. The 100 K structure is publishable, but the 250 K structure has very low data completeness, and too few observed data for a meaningful refinement -the observed data:parameter ratio is only 6.5:1. That explains the very low precision of that structure (Table 5, supporting information). There is also obvious disorder in the prentrz ligands at that temperature, which hasn't been modelled; in fact, it can't be modelled with such a weak dataset. The basic interpretation of that structure is doubtless correct, but I wouldn't publish such a low quality crystal structure without a good reason. In fact, the 100 K structure gives all the information needed to interpret the magnetic data of 1.nqp, so my choice would be to remove the 250 K structure from the manuscript. In any case, the authors should comment on the low quality diffraction shown by 1.nqp -it's not truly a single-crystal-to-single-crystal transformation if the crystal degrades badly during the process.
(iii) Why is the spin-transition at Fe(2) in 1.nqp incomplete? It probably isn't kinetically trapped, as the transition temperature is too high for that.
(iv) It looks like there is strong preferred orientation in the powder diffraction data in Figures 7-10 of the SI. That doesn't invalidate the measurements but it should be explained -were those samples true powders, or crystals? (vi) The text says Rietveld refinements were obtained for both phases (line 96), but only 1.lcp is included in the SI (Figure 18). The Rietveld refinement for 1.nqp should be added to the revision.
(vii) I know of one other spin-crossover material, where different phases coexist in the same crystal during a desolvation process (Chem. Sci. 2016, 7, 2907. That should be cited in the revision. (viii) 'lcp' and 'nqp' are non-standard abbreviations. They are defined in the Abstract, but they should also be defined in the main text so the reader easily understands what they mean.
Figures were modified according to your suggestions. We believed these new evidences are sufficient to support our claim.
1. Single-crystal X-ray diffraction data for 1-lcp phase lead to structure solutions that show very large residual electron density in the proximity of the palladium ion. Authors use hundreds of OMIT instructions (more than 700 in case of 1-lcp at 150 K) in order to artificially remove this electron density, which is a case of data manipulation that should never be performed. Instead, an adequate twin law should be applied to systematically remove electron density attributed to the twinned crystal or the experiment itself should be repeated (comments 3 and 5).

In the SI:
Supplementary  Table R1 and Fig. R1a) and its SCO property is different from the single crystal of 1·9/2H2O (Fig. R1b).
Our primary experiment shows the spin equilibrium of the pristine single crystal can be affected by the methanol molecules, and a further experimental and theoretical study is in progress to investigate the intercorrelation between the molecular dynamic and spin equilibrium. As the quality of single-crystal structural refinements has been significantly improved and the structure of pristine crystals is independent from the conclusion of this manuscript, it would be better that the structure of pristine crystals and detailed magnetic property can be presented together with a thorough mechanistic explanation in a future study.
As you suggested, the pristine crystals should involve in a partial exchange of crystallization solvent when they are exposed in the air.  Fig. 1.  To clarify this point, the sentence in the manuscript have revised as below: Page 4: Notably, an attempt to obtain the crystal structure of completely dehydrated crystal of 1 failed because of the poor diffraction of anhydrous crystal of 1.
6. Water adsorption isotherm depicted in the Figure 2A may be influenced by partial sample decomposition, resulting from very long activation at high temperature (please compare with Figure 4 in the SI). The identity of the sample should be re-tested by PXRD measurement after water sorption experiment.

Response:
To verify the adsorption isotherm depicted in the Figure  The new result has been added in the SI as Supplementary Fig. 11.

Supplementary Fig. 11 PXRD patterns of samples before (Blue) and after (Green) two adsorption isotherm experiments and the continuous adsorption-desorption-cycles measurement. A, The PXRD
pattern of sample after two isothermal vapor ad/de-sorption (in the Fig. 2A  7. 1·4/3H2O line in the Figure 2C actually corresponds to 5/3H2O level, which is misleading to the reader and should be corrected. Moreover the "Uptake" drops down to -0.2 mol/mol for 1200 min., which may be another sign of partial sample decomposition at 450 K and undermines validity of this plot.

Response:
We have corrected the misleading line in Figure 2C. The abnormal drop of "Uptake" line at 1200 were performed on single crystals.
In the micro-Raman spectra, the peaks at 1160 and 1178 cm -1 denote the structure of nqp phase and a single broad peak at 1159 cm -1 denote the structure of lcp phase. In the pure nqp single crystal, the peaks at 1160 and 1178 cm -1 persisted up to 3 days in saturated steam, and then converted to lcp structure. While for a single crystal in phase-coexistence state, the peaks that denote to nqp structure can change to a single broad peak within 10 min in a humidity of 80%. The distinct responses of pure nqp single crystal and phasecoexistence single crystal in the micro-Raman spectra verify the phase-coexistence dependent water adsorption property in this material.

These results have been added in the manuscript and SI as below:
In the manuscript:

Page 6: Phase-coexistence state investigated by SC-XRD and micro-Raman spectroscopy analyses.
The phase-coexistence state of individual crystal is directly supported by single-crystal diffraction analyses.
The crystal lattices of both nqp and lcp phases can be indexed in reciprocal space from the data collected on a partially desolvated single crystal at 310 K (Supplementary Fig. 19 and 9. Page 7, lines 148-150: "the phase-coexistence state works on individual crystals rather than a physical mixture of two pure phases because the PXRD patterns of a physical mixture of the lcp phase 1·9/2H2O and nqp phase 1·4/3H2O did not show any significant change after spraying the water mist Supplementary   Fig. 14)". This conclusion is in contradiction to the water adsorption isotherm ( Figure 2B) which clearly shows that nqp-to-lcp transition appears above P/P0 = 0.8. Lack of significant changes in the PXRD may simply result from limited vapor diffusion or too short stabilization time.

Response:
The sentence of Page 7, lines 148-150 ~~~ is not in contradiction to the water adsorption isotherm in Figure 2B, because the sample of Figure 2B, which was prepared by left the pure nqp phase in the steam atmosphere (P/P0 = 0.9) for four days and then activated under vacuum at 298 K for 6 h, is in a phase-coexistence state. Although the PXRD pattern of physical-mixture sample is similar with the phasecoexistence sample, the adsorption property of former is obviously different from the latter. Such distinct phenomenon is highly consistent with our assumption that the phase-coexistence state of individual crystals plays essential roles in the gate-opening adsorption.
To confirm the lack of significant changes in the PXRD pattern of physical-mixture sample is not own to the limited vapor diffusion or too short stabilization time, we measured the water adsorption isotherm of this sample with the same experimental condition (activated under vacuum at 298 K for 6 h). As shown in Figure   below (down panel of Figure 2A), the uptake of ~2.7 H2O per Fe II of this physical mixture sample is lower than that of ~2.7 H2O per Fe II for phase-coexistence sample (middle panel of Figure 2A), suggesting the nqp phase of physical-mixture sample cannot recover to lcp phase and phase-coexistence state of individual crystals plays essential roles in the gate-opening adsorption.
However, the difference between samples in Figure 2a and 2b is not well illuminated in our previous manuscript, therefore, some important information was added in the Figure 2 to avoid the confusion.
Moreover, we think the different adsorption property of physical-mixture sample and phase-coexistence sample is important to support our assumption and we inserted the Supplementary Fig. 14 into Figure 2  11. Magnetic measurements seem to contradict the hypothesis of phase-coexistence in single crystals of Figure 3A and Figure 3E/3F. This would be highly unexpected for the phase-coexistence within single crystal, as SCO in this system is highly cooperative. Moreover, small changes in water content may very strongly influence SCO  Figure 3A and Figure 3E 12. Sample preparation for magnetic measurements should be described in details in the discussion of magnetic properties (exact conditions of sample stabilization that lead in preparation of each phase mixture). This comment is answered together with comment 14.

Figures 3B-D look like linear combinations of curves presented in
14. Methods section should contain detailed description of sample packing for magnetic measurements.
How was the sample stability achieved? There are also several minor issues that should be corrected: 1. Page 2, line 16: "…leads to a pore rearrangement associated with local negative adsorption". No negative adsorption is observed for the presented network and therefore this part of the sentence is an unnecessary exaggeration. The observed behavior is pore rearrangement only and the new term "local negative adsorption" should not be coined.
Response: According to your suggestion, the "local negative adsorption" was deleted and the sentence have been modified as below: Page 1: In this material, the adsorption-induced, non-uniform pedal motion of the axial prentrz ligands and the crumpling/unfolding of the layer structure actuate a reversible narrow quasi-discrete pore (nqp) to large channel-type pore (lcp) change that leads to a pore rearrangement associated with simultaneous pore open and close.
Page 3: The "local negative adsorption" in the manuscript was also modified.
2. The first paragraph of the introduction section is not clear and especially lines 30-40 need rephrasing.

Response:
The introduction section was rewritten as below:

In the manuscript:
Page 3: The 2D coordination networks were assembled further via intermolecular interactions into a 3D porous structure with channel pores (13.2  4.4 Å 2 ) extending along the crystallographic a-axis ( Fig. 1C and Supplementary Fig. 4, regardless of the vander Waals radii) 48,49 .  8. I lack the expertise to evaluate details of DFT calculations, but I was alerted by the following description: "The experiment obtained two crystal structures […] the other is lcp phase structure with 10 water molecules in the unit cell, denoted as lcp-10w". Why 10 water molecules were assumed in DFT calculations, whereas there are 9 water molecules in the crystal structure of 1-lcp?
Response: According to the SC-XRD data of lcp phase 1·9/2H2O, some guest water molecules in the pores are disordered with a partial occupancy, which may affect the structural optimization implemented in the Vienna ab initio simulation package (VASP 5.4.4). According to the calculation result, lcp phase structure with 10 water molecules in the unit cell is reasonable for saturated adsorption state. More importantly, the number of water molecules, 9 or 10, has no influence on the procedure of adsorption-induced nqp-to-lcp lattice transformation.
This information was added in the SI as below: The optimized lcp phase structure contains 10 water molecules in the unit cell, which reflects the disorder state of guest water molecules in the pores. The number of water molecules, 9 or 10, has no influence on the procedure of adsorption-induced nqp-to-lcp lattice transformation.

Response to reviewer #2:
Comments to Authors: This manuscript reports a new example of an iron/palladium 2D Hoffmann network structure with 1D porosity.
Such compounds have been heavily studied by the spin-crossover materials community for the past 20 years. They are well-known to afford interesting and useful thermal spin-transitions, which may be coupled to the removal or exchange of guest molecules within their pore structure. This is another example. It can be isolated in two different hydration states, which can be interconverted in single-crystal-to-single-crystal fashion. The two forms have very different pore structures and must interconvert via a detectable, metastable intermediate phase. That leads to gating during the interconversion of the two phases, which allows the mechanism of the interconversion to be monitored in unusual detail.
The design of the material is unexceptional, and single-crystal-to-single-crystal reactions in spincrossover crystals are also quite well known now. Rather, the main interest lies in the complicated mechanism of the pore rearrangement between the phases, and how this manifests in the spin-transitions of the different phases. This has been thoroughly characterized by diffraction, by adsorption isotherms, and by periodic DFT calculations.
The authors have done a lot of experiments to sort this out. Some data aren't of the highest quality, but it's clear their interpretation and conclusions are sound. This is also novel enough for the journal, and it can be published if the following comments are addressed:

Response: We thank this reviewer for positive comments on our work and valuable suggestions concerning the manuscript. Our point-by-point responses are provided below.
1. The microanalyses of the two phases are good. However, a straightforward check would be to run thermogravimetric analyses (TGAs) on the two phases, as an extra confirmation of their water content.
I was surprised those weren't included in the SI, and they should be added to the revision.

Response: Thank you for pointing out the question. We performed the thermogravimetric (TG)
measurements to further determine the guest content of the pristine crystal, lcp phase 1·9/2H2O and nqp phase 1·4/3H2O.
In SI:
2. The crystal structures of the 1-nqp phase are of low quality. The 100 K structure is publishable, but the 250 K structure has very low data completeness, and too few observed data for a meaningful refinement -the observed data : parameter ratio is only 6.5 : 1. That explains the very low precision of that structure (Table 5, supporting information). There is also obvious disorder in the prentrz ligands at that temperature, which hasn't been modelled; in fact, it can't be modelled with such a weak dataset.
The basic interpretation of that structure is doubtless correct, but I wouldn't publish such a low quality crystal structure without a good reason. In fact, the 100 K structure gives all the information needed to interpret the magnetic data of 1-nqp, so my choice would be to remove the 250 K structure from the manuscript.
In any case, the authors should comment on the low quality diffraction shown by 1-nqp -it's not truly a single-crystal-to-single-crystal transformation if the crystal degrades badly during the process.  Fig. 4C and Supplementary Fig. 23 and Table 6).

In the SI:
Supplementary K) or exposed to vacuum, peaks denoting the nqp phase appeared within 1 minute and increased gradually with time ( Fig. 2C and Supplementary Figs. 12-14).
Changes made on the Supplementary Fig. 12 note: 6. The text says Rietveld refinements were obtained for both phases (line 96), but only 1-lcp is included in the SI (Figure 18). The Rietveld refinement for 1-nqp should be added to the revision.  2907-2915 (2016).

Response
8. 'lcp' and 'nqp' are non-standard abbreviations. They are defined in the Abstract, but they should also be defined in the main text so the reader easily understands what they mean.
Response: According to your suggestion, the abbreviations were added in the revised manuscript.
Page 3: The atypical pore transformation is accompanied by a distinct adsorption process in which a stable phase-coexistence state, where narrow quasi-discrete pore (nqp) and large channel-type pore (lcp) phases are concomitant in an individual crystal, needs to be activated first by long-time exposure in saturated steam to accomplish the nqp-to-lcp gate-opening transition.
Reviewer #1 (Remarks to the Author): The resubmitted manuscript contains improved experimental data when compared with the initial submission. Authors repeated single-crystal X-ray diffraction experiments using synchrotron radiation and conducted Raman spectroscopy experiment with dehydration/rehydration. They also included missing TGA experiments, additional water adsorption isotherm (Fig 2A, "Physical mixture") and clarification of some important experimental details. This allows for independent validation of experiments. Analysis of the data leads to the conclusion, that the described framework clearly demonstrates activation-method dependent adsorption properties. After long activation at 433 K in vacuum it shows only limited water adsorption, but water uptake is doubled in case of low temperature activation. This is depicted in Figure 2A and Figure 3.
I believe that experimental results presented in the revised manuscript are interesting, but I still disagree with the interpretation of these results. In my opinion additional measurements confirm lack of phase-coexistence within the single crystal. The observed sorption switching seems to result rather from the physical differences between anhydrous 1, 1·4/3 H2O ("nqp phase") and 1·9/2H2O ("lcp phase"). This conclusion is based on the following points [numeration of rows in the revised manuscript]: 1) Authors describe different methods of preparation for anhydrous 1 and for "nqp phase" which was characterized using scXRD as 1·4/3H2O. The first one is prepared "by heating 1·9/2H2O at 433 K for 48 h under vacuum" and is only weakly crystalline ("an attempt to obtain the crystal structure of completely dehydrated crystal of 1 failed because of the poor diffraction") [lines 97-99]. Weak crystallinity of 1 is also reflected by large peak broadening in powder X-ray diffraction ( Supplementary  Fig. 8). On the other hand "crystals of the nqp phase 1·4/3H2O were obtained by heating 1·9/2H2O to 433 K for 48 h under vacuum and cooling in air." [lines 83-84]. This 1·4/3H2O "nqp phase" shows good crystallinity, as evidenced by single-crystal X-ray diffraction and PXRD pattern ( Supplementary  Fig. 9b). Therefore it is evident that 1 and 1·4/3H2O are not chemically identical. This is a very important observation for the later part of the discussion.
2) Authors claim that 1 and 1·4/3H2O share the same framework: "in situ generated 1 […] possessed the same framework as that of 1·4/3H2O in the nqp phase ( Supplementary Fig. 8)" [lines [96][97][98]. It is worth noting, that they are not identical -experimental PXRD pattern for 1 depicted in Supplementary  Fig. 8 differs from the simulated pattern for 1·4/3H2O and these differences do not seem to be caused by preferred orientation of crystallites only. It may be difficult to evaluate due to the peak broadening observed for 1. Still, I believe that 1 and 1·4/3H2O share similar "narrow quasi-discrete pore" structure type, but they are not exactly the same phases.
3) 1 and 1·4/3H2O share the same position of the first diffraction peak at around 6.6 degrees 2theta. Therefore it is impossible to distinguish 1 from 1·4/3H2O by comparing 5-15 degrees 2theta range only, despite of the fact that they are two chemically different phases (as explained in point 1). Figure 2A, top panel: The water sorption isotherm is labelled as "Pure nqp phase". Throughout the manuscript authors use "nqp phase" for the description of 1·4/3H2O. On the other hand, caption to Figure 2A reads: "A, Isothermal vapor adsorption (solid red) and desorption (open red) of the sample activated at 433 K under vacuum for 48 h (up)". This is supported by: "In the first measurement, the 1·9/2H2O sample was activated in situ at 433 K under vacuum for 48 h and then measured at 298 K" [lines 311-312] These activation conditions do not lead to 1·4/3H2O, but to anhydrous 1, as explained in point 1 of this review and specified by authors themselves (lines 97-99). Therefore I believe that top panel of Figure 2A shows pore filling of "nqp structure type", which starts with compound 1 at p/p0 = 0 and proceeds to ≈4/3H2O molecules per Fe water uptake at p/p0 = 0.9, which corresponds to compound 1·4/3H2O. Moreover, please note that water adsorption isotherm starts with a flat plateau in p/p0 = 0-0.08 range. This adsorption behavior may indicate transition from closed pore structure to the narrow quasi-discrete pore structure, corresponding to the transition from 1 to 1·4/3H2O. As there is no such plateau in the water desorption isotherm, structure would probably remain in this narrow quasi-discrete pore structure type in the desorption branch. This is confirmed by powder X-ray diffraction results. PXRD pattern of the sample after isothermal cycle of water sorption for the sample activated at 433 K under vacuum for 48 h ( Supplementary Fig. 11) is not the same as PXRD pattern for the sample activated at 433 K under vacuum for 48 h (SupplementaryFig. S8). Figure 2A, middle panel: The water sorption isotherm was measured for "the 1·9/2H2O sample activated at 298 K under vacuum for 6 h" [lines [314][315]. State of the sample after this kind of activation cannot be determined reliably, as there is no PXRD pattern registered under exactly the same conditions and thus my conclusions are based on water sorption isotherm. Please note, that there is no sign of inflection at p/p0 = 0.1. While authors attribute this to the appearance of the phasecoexistence state of 1·4/3H2O and 1·9/2H2O, I believe this results simply from the absence of anhydrous 1 in that sample. The shape of the water isotherm is well explained by initial monolayer adsorption within the evacuated "large channel pore" structure type at low p/p0, which is followed by hysteretic capillary condensation in the micropores. Remarks 1-6 lead me to the following conclusion: 1·9/2H2O shows the "large channel pore" type of structure, where approximately 3 water molecules per Fe can be evacuated in mild conditions with little effect to the coordination skeleton. When this compound is heated at 433 K for a long time it is transformed into anhydrous 1, which was not characterized by scXRD, but possibly has the "narrow quasi-discrete pore" structure, or even shows completely closed pores (please see point 4 of this review). Anhydrous 1 relatively quickly absorbs approximately 1.5 water molecule per Fe, at high humidity producing well-crystalline 1·4/3H2O. However, transformation of "nqp" structure to "lcp" structure requires several days in high humidity, producing fully hydrated 1·9/2H2O. This fully explains top panel of Figure 2A (which shows equilibrium between anhydrous 1 and structurallycharacterized 1·4/3H2O) and middle panel of Figure 2A (which shows equilibrium between evacuated "lcp" structure and structurally-characterized 1·9/2H2O). Slow dynamics between nqp and lcp structures (which is in line with high nqp-lcp energy barrier calculated by the authors) fully explains water sorption data, without a need to employ the elusive "phase-coexistence state". Moreover, other measurements also indicate lack of this phase-coexistence within a single crystal: 7) In accordance with my previous review, I believe that phase-coexistence within a single crystal can be tested only with a spatially resolved method. Authors utilized Raman spectroscopy to conduct such an experiment on a single crystal. Again the identity of the "nqp phase" is not clear. It was dried at 433 K for 48 hours ( Supplementary Fig. 21), which depending on the cooling conditions (dry or humid air) would produce anhydrous 1 or 1·4/3H2O, but cooling conditions were not specified. Regardless of the hydration state, both these compounds are expected to show "nqp" structure, which very slowly transforms into "lcp" structure in water vapor. This explains why 4 days in saturated stream were required to observe the transformation. 8) Figure 3 shows spatially resolved experiment, where 4 different areas of a single crystal were tested (C-F). All these positions shows very similar Raman spectra after N2 purge (G-J) and exactly identical Raman spectra after rehydration (K-N). This is exactly opposite, to what should be observed in case of phase-coexistence. In such a case, spectra depicted in Fig. 3G-J would be very different, as some of them would resemble "lcp" structure type, and the others would resemble "nqp" structure type. In fact, no spectra in Fig. 3 resembles "nqp" structure type. All spectra in the Fig. 3G-N show the same intensity of two bands around 1400 cm-1. For comparison, in the Raman spectrum of "nqp" structure depicted in Supplementary Fig. 21 band at ≈1390 cm-1 has twice the intensity of that at ≈1410 cm-1. The variation between Figure 3G-J and K-N seems to result from differences between fully hydrated "lcp structure" (1·9/2H2O) and evacuated "lcp" structure, with little effect to the coordination skeleton and no presence of 1·4/3H2O. Again, this experiment demonstrated different water adsorption dynamics for "nqp" structure and "lcp" structure, but not the existence of "nqp" and "lcp" structure within a single crystal. 9) One may argue that PXRD patterns combined with adsorption measurements seem to confirm phase-coexistence conclusion. However, as noted in point 3 of this review, the first diffraction peak is very misleading, as it is in the same position for 1 and 1·4/3H2O. Please see for example Supplementary Fig. S15 -only two phases are accounted for: 1·9/2H2O "blue" and 1·4/3H2O "red". Thus, the same "red" phase (1·4/3H2O) is assigned to patterns labelled as 360 min. and 2880 min., despite the vast difference in 15-30 degrees 2theta region. This makes analysis of this first diffraction peak in PXRD patterns very misleading and it may result in wrong conclusions about phase identity of the sample. I believe that PXRD pattern labelled as 2880 min. was obtained for the sample mostly composed of anhydrous 1.

5)
10) "The SCO performances of phase-coexistence samples can be regarded as linear combinations of SCO transitions of 1·9/2H2O and 1·4/3H2O, and this phenomenon is significantly different from typical SCO compounds whose SCO behaviors are usually globally influenced by small changes in water content, suggesting the existence of interfaces between the lcp and nqp phases that interrupt the diffusion of lattice from lcp to nqp phase." [lines 214-221] I strongly disagree with this conclusion. When properties of the mixture resemble linear combination of the ingredients, this means that there is no interaction between the ingredients. Physical mixture of 1·9/2H2O and FeCl2 will show linear combination of their magnetic properties, despite of the fact that 1·9/2H2O and FeCl2 do not show phase-coexistence within single crystals. It is well known that cooperative SCO (as observed for 1·9/2H2O) is strongly affected by variation in crystallite size and similar interface effects. Thus existence of the interface between the lcp and the nqp is expected to affect magnetic properties of both phases, which is not observed in the data.
In conclusion, I believe that the resubmitted manuscript contains mostly valid measurements (unfortunately PXRD patterns suffer from strong texture, but that results from the experimental setup) and the observed phenomenon of "programmable" sorption is interesting, with the "lcp" structure showing twice the water uptake of the "nqp" structure. However, analysis of the resubmitted version led me to the conclusion, that this behavior can be fully explained by slow lcp-nqp dynamics. In my opinion there is no evidence for phase-coexistence within the single crystals of this material. Therefore I encourage the authors to re-analyze relevant measurements and prepare a revised text, with emphasis on the interconversion between anhydrous 1, "nqp" structure type and "lcp" structure type", rather than questionable phase-coexistence phenomenon (in my opinion no additional measurements are necessary to fully describe behavior of this framework in the absence of phasecoexistence hypothesis).
Additional comments: 11) "the decomposition of framework of 1 should be precluded, as we can re-obtained the crystal structure of 1·4/3H2O by exposing one of the above single crystals in the air" [rebuttal, page 11] The ability to re-obtain the crystalline form by re-solvation does not confirm the stability of the parent framework. Recently there were several reports regarding solvent-driven transformation from amorphous to crystalline state (Dalton Trans., 2018, 47, 845;J. Am. Chem. Soc. 2021, 143, 20202 and for cyanides: Chem. Sci., 2021, 12, 9176). Fig. 11 -it would be more appropriate to compare the sample after sorption experiments with the already activated sample (Supp. Fig. S11A -I believe that PXRD pattern from Supp. Fig. S8 may be used for that).

12) Supporting
13) On several occasions experimental patterns were compared to the simulated pattern for 1.4/3H2O at 100 K (for example Supp. Fig. S13) -please replace it with the simulated pattern for structure at 250 K.
15) Article, page 14 -in the description of Raman setup milimeters should probably be replaced with micrometers.
Reviewer #2 (Remarks to the Author): Many of reviewer 1's comments on the original manuscript, and some of mine, concerned the crystallography. That has been addressed by remeasuring or re-refining all the structures in the study, including some new data collections with synchrotron radiation. The new structural data are a significant improvement on the originals, and the many of the experimental issues itemised by reviewer 1 have now been addressed. The new crystal structures from the nqp phase are of reasonable quality, for the product of a single-crystal-to-single-crystal annealing reaction.
The revision also includes new thermogravimetric analyses and extra magnetic data (which I requested), and single crystal Raman microscopy (to address a comment by reviewer 1). Those are all helpful additions.
I have just a few new comments to address before final acceptance of the manuscript.
(i) My only criticism of the new data, is that the Raman microscopy data in Supplementary Figure 23 don't clearly show the co-existence of both phases in the same crystal, as proposed in the caption. Spectra E-H all look the same; I-L all look the same; and M-P all look the same. So, the phase composition at all four points of the crystal looks the same, under each of the conditions measured.
So, that experiment was worth doing, but it doesn't prove the two phases can co-exist in the same crystal, at the same time.
At best, what it shows is that the domains of the two phases in the mixedphase crystal must be smaller than the resolution of the Raman microscope. The caption to Supplementary Figure 23, and the description on lines 167-175, should be changed to reflect that.
Supplementary Figure 19 does show the two phases can co-exist in the same crystal, though, so that conclusion is sound on a macroscopic level, even if it was not observed microscopically.
(ii) Line 153. The abbreviation 'SCP' is not in common use, and isn't defined anywhere. The 'CP' is presumably Coordinated Polymer, but I don't know what the 'S' stands for. Since it isn't used anywhere else in the manuscript, that abbreviation should be changed for something more obvious.
(iii) An English error that comes up several times is "pore open and close", which should be changed to "pore opening and closing".
More generally, while the manuscript is always understandable, there are many small English mistakes and the text would benefit from English corrections at the proof stage.

Responses to reviewers' comments
We are grateful to all reviewers for their thorough evaluation of our revised manuscript "Single crystal-tosingle crystal and spin-crossover transformations via phase-coexistence state in pore-adjustable frameworks" (NCOMMS-21-40232A). Their kind comments and constructive suggestions would highly help us improve the quality of our manuscript. Now, we have completed revision and addressed all questions raised by all reviewers. We have changed the manuscript title into "A spin-crossover framework endowed with pore-adjustable behavior by slow structural dynamics". In this 2 nd revised manuscript and supplementary material, all changes have been highlighted in yellow. Our point-by-point responses to all reviewers' comments are listed below, shown in italic and red.

Responses to reviewer #1:
Comments to Authors: The resubmitted manuscript contains improved experimental data when compared with the initial submission.
Authors repeated single-crystal X-ray diffraction experiments using synchrotron radiation and conducted Raman spectroscopy experiment with dehydration/rehydration. They also included missing TGA experiments, additional water adsorption isotherm (Fig 2A, "Physical mixture") and clarification of some important experimental details. This allows for independent validation of experiments. Analysis of the data leads to the conclusion, that the described framework clearly demonstrates activation-method dependent adsorption properties. After long activation at 433 K in vacuum it shows only limited water adsorption, but water uptake is doubled in case of low temperature activation. This is depicted in Figure 2A and Figure 3.
I believe that experimental results presented in the revised manuscript are interesting, but I still disagree with the interpretation of these results. In my opinion additional measurements confirm lack of phasecoexistence within the single crystal. The observed sorption switching seems to result rather from the physical differences between anhydrous 1, 1·4/3H2O ("nqp phase") and 1·9/2H2O ("lcp phase"). This conclusion is based on the following points: Response: Thanks for providing your meticulous and very valuable comments. We agree with your viewpoint of slow lcp-nqp dynamics, so we have carried out comprehensive consideration and made detailed changes about the "phase-coexistence state" description.
We now use "partially dehydrated sample" instead of 'phase-coexistence state' to refer to the samples with mild activation, and emphasize "activation-method dependent adsorption properties are caused by slow nqp-lcp dynamics and essentially determined by the pore rearrangement associated with simultaneous pore opening and closing." in the revised manuscript.
The phrase "partially dehydrated sample" conforms to the core point of slow lcp-nqp dynamics, the reasons are shown below: 1) When the crystal sample of 1·9/2H2O in lcp phase was subjected to mild activation, i.e., thermal treatment (323 K) or exposed to vacuum, new peaks appeared in the higher-angle region within 1 minute and increased gradually with time, indicating the contraction of partially dehydrated framework (Fig. R1, ref. Science 2010, 329, 1053).   Fig. 9b).
Therefore it is evident that 1 and 1·4/3H2O are not chemically identical. This is a very important observation for the later part of the discussion.  Fig. 8)."
2. Authors claim that 1 and 1·4/3H2O share the same framework: "in situ generated 1 […] possessed the same framework as that of 1·4/3H2O in the nqp phase ( Supplementary Fig. 8)" [lines 96-98]. It is worth noting, that they are not identical -experimental PXRD pattern for 1 depicted in Supplementary Fig. 8 differs from the simulated pattern for 1·4/3H2O and these differences do not seem to be caused by preferred orientation of crystallites only. It may be difficult to evaluate due to the peak broadening observed for 1. Still, I believe that 1 and 1·4/3H2O share similar "narrow quasi-discrete pore" structure type, but they are not exactly the same phases.

Response:
The caption for Supplementary Fig. 8 has been changed into " Supplementary Fig. 8 In situ PXRD patterns of 1 upon heating the dried sample at 433 K for 48h under vacuum (Green, the heating rate of 5 K min -1 ) compared with that of 1·4/3H2O (Red). The PXRD data of 1 was collected at room temperature after activated treatment.".

1 and 1·4/3H2O
share the same position of the first diffraction peak at around 6.6 degrees 2theta.
Therefore it is impossible to distinguish 1 from 1·4/3H2O by comparing 5-15 degrees 2theta range only, despite of the fact that they are two chemically different phases (as explained in point 1).

Response:
Thank you for your comment. By comparing 5-40 degrees 2theta range of 1 and 1·4/3H2O, they are not exactly the same phases ( Supplementary Fig. 8).
4. Figure Figure 2A shows pore filling of "nqp structure type", which starts with compound 1 at p/p0 = 0 and proceeds to ≈4/3H2O molecules per Fe water uptake at p/p0 = 0.9, which corresponds to compound 1·4/3H2O. Moreover, please note that water adsorption isotherm starts with a flat plateau in p/p0 = 0-0.08 range. This adsorption behavior may indicate transition from closed pore structure to the narrow quasi-discrete pore structure, corresponding to the transition from 1 to 1·4/3H2O. As there is no such plateau in the water desorption isotherm, structure would probably remain in this narrow quasi-discrete pore structure type in the desorption branch. This is confirmed by powder X-ray diffraction results. PXRD pattern of the sample after isothermal cycle of water sorption for the sample activated at 433 K under vacuum for 48 h ( Supplementary Fig. 11) is not the same as PXRD pattern for the sample activated at 433 K under vacuum for 48 h ( Supplementary Fig. S8).

Response:
Thank you for your meticulous examination. As you suggested, we have rearranged the structural transformation during the activation-method dependent adsorption. This information has been amended in the Figure 2 legend and Supplementary Fig. 18. The sentences "After that, it showed water adsorption with a threshold pressure of P/P0 = 0.08 ( Fig. 2A, up)." have been changed into "After that, the water adsorption isotherm started with a flat plateau in P/P0 = 0-0.08 range. The adsorption behavior may indicate structural transformation from closed framework to nqp framework, corresponding to the transition from 1 to 1·4/3H2O ( Fig. 2A, up)." (lines 3-6, page 5).
In addition, the caption for Figure 2 has also been modified, see below marked in yellow.  Fig. 18 has also been modified, as shown below: Supplementary Fig. 18 Activation-method dependent water-adsorption (Red lines: desorption; Blue lines: adsorption).

Fig. 2 Water adsorption isotherms and corresponding structural transformations probed by PXRD. A,
5. Figure 2A,  and 1·9/2H2O, I believe these results simply from the absence of anhydrous 1 in that sample. The shape of the water isotherm is well explained by initial monolayer adsorption within the evacuated "large channel pore" structure type at low p/p0, which is followed by hysteretic capillary condensation in the micropores.
Response: According to the TG measurement, the sample is partially dehydrated and we agree that the partially dehydrated sample does not contain the anhydrous 1. We think that "partially dehydrated sample/framework" is a better description of the sample with mild activation than "phase-coexistence state" or "evacuated lcp structure type". Firstly, we agree that the sample with mild activation has the structural characteristics of lcp structure type, which is not contradictory with the "partially dehydrated sample/framework". Secondly, a small amount of solvent remains in the samples with mild activation. Thirdly, when the crystal sample of 1·9/2H2O in lcp phase was subjected to mild activation, i.e., thermal treatment (323 K) or exposed to vacuum, new peaks appeared in the higher-angle region within 1 minute and increased gradually with time, indicating the contraction of partially dehydrated framework (Fig. R1, ref. Science 2010, 329, 1053. The sentences "When the crystal sample of 1·9/2H2O in lcp phase was subjected to thermal treatment (> 323 K) or exposed to vacuum, peaks denoting the nqp phase appeared within 1 minute and increased gradually with time ." and "These results suggest that the lcp phase can persist in the sample prepared under mild activating conditions, and such a lcp and nqp phasecoexistence state plays a vital role in the guest adsorption associated with pore transformation from the nqp phase to the lcp phase 31 ." have been changed into "When the crystal sample of 1·9/2H2O in lcp phase was subjected to mild activation, i.e., thermal treatment (323 K) or exposed to vacuum, new peaks appeared in the higher-angle region within 1 minute and increased gradually with time, indicating the contraction of partially dehydrated framework (Fig. 2C and Supplementary Figs. 5,(12)(13)(14)." Page 6]. Remarks 1-6 lead me to the following conclusion: 1·9/2H2O shows the "large channel pore" type of structure, where approximately 3 water molecules per Fe can be evacuated in mild conditions with little effect to the coordination skeleton. When this compound is heated at 433 K for a long time it is transformed into anhydrous 1, which was not characterized by scXRD, but possibly has the "narrow quasi-discrete pore" structure, or even shows completely closed pores (please see point 4 of this review). Anhydrous 1 relatively quickly absorbs approximately 1.5 water molecule per Fe, at high humidity producing well-crystalline 1·4/3H2O. However, transformation of "nqp" structure to "lcp" structure requires several days in high humidity, producing fully hydrated 1·9/2H2O. This fully explains top panel of Figure 2A (which shows equilibrium between anhydrous 1 and structurally-characterized 1·4/3H2O) and middle panel of Figure 2A (which shows equilibrium between evacuated).  Fig. 21), which depending on the cooling conditions (dry or humid air) would produce anhydrous 1 or 1·4/3H2O, but cooling conditions were not specified. Regardless of the hydration state, both these compounds are expected to show "nqp" structure, which very slowly transforms into "lcp" structure in water vapor. This explains why 4 days in saturated stream were required to observe the transformation. 8. Figure 3 shows spatially resolved experiment, where 4 different areas of a single crystal were tested (C-F). All these positions shows very similar Raman spectra after N2 purge (G-J) and exactly identical Raman spectra after rehydration (K-N). This is exactly opposite, to what should be observed in case of phase-coexistence. In such a case, spectra depicted in Fig. 3G-J would be very different, as some of them would resemble "lcp" structure type, and the others would resemble "nqp" structure type. In fact, no spectra in Fig. 3 resembles "nqp" structure type. All spectra in the Fig. 3G-N show the same intensity of two bands around 1400 cm-1. For comparison, in the Raman spectrum of "nqp" structure depicted in Supplementary Fig. 21 band at ≈1390 cm-1 has twice the intensity of that at ≈1410 cm-1. The variation between Figure 3G-J and K-N seems to result from differences between fully hydrated "lcp structure"

Response
(1·9/2H2O) and evacuated "lcp" structure, with little effect to the coordination skeleton and no presence of 1·4/3H2O. Again, this experiment demonstrated different water adsorption dynamics for "nqp" structure and "lcp" structure, but not the existence of "nqp" and "lcp" structure within a single crystal.
Response: According to your suggestion, we have re-analyzed the Raman spectrum in details and the sentence in the manuscript have been revised.
Lines 24-27 in page 6 and lines 1-7 in page 7 of the revised manuscript: In order to further verify that the activation-method dependent adsorption properties are related to structural difference between nqp and partially dehydrated frameworks, micro-Raman spectra experiments (spot diameter ~2 m) were performed on single crystals 56,57 . As shown in Supplementary Fig. 19 Fig. 19 Micro-Raman spectra of 4-amino 2,cinamyle aldehyde,prentrz ligand,K2Pd(CN)  9. One may argue that PXRD patterns combined with adsorption measurements seem to confirm phasecoexistence conclusion. However, as noted in point 3 of this review, the first diffraction peak is very misleading, as it is in the same position for 1 and 1·4/3H2O. Please see for example Supplementary Fig. S15 -only two phases are accounted for: 1·9/2H2O "blue" and 1·4/3H2O "red". Thus, the same "red" phase (1·4/3H2O) is assigned to patterns labelled as 360 min. and 2880 min., despite the vast difference in 15-30 degrees 2theta region. This makes analysis of this first diffraction peak in PXRD patterns very misleading and it may result in wrong conclusions about phase identity of the sample. I believe that PXRD pattern labelled as 2880 min. was obtained for the sample mostly composed of anhydrous 1.

Response:
In the previous Supplementary Fig. 15 The caption for Fig. 2 has also been modified (see the response to question no. 4).
Supplementary Fig. 15 has also been modified, as shown below: Supplementary Fig. 15 The full PXRD patterns during the water desorption-adsorption process. In conclusion, I believe that the resubmitted manuscript contains mostly valid measurements (unfortunately PXRD patterns suffer from strong texture, but that results from the experimental setup) and the observed phenomenon of "programmable" sorption is interesting, with the "lcp" structure showing twice the water uptake of the "nqp" structure. However, analysis of the resubmitted version led me to the conclusion, that this behavior can be fully explained by slow lcp-nqp dynamics. In my opinion there is no evidence for phasecoexistence within the single crystals of this material. Therefore I encourage the authors to re-analyze relevant measurements and prepare a revised text, with emphasis on the interconversion between anhydrous 1, "nqp" structure type and "lcp" structure type", rather than questionable phase-coexistence phenomenon (in my opinion no additional measurements are necessary to fully describe behavior of this framework in the absence of phase-coexistence hypothesis).
Response: Thank you for the recognition of innovation in this work and the valuable suggestions concerning the manuscript. We have re-analyzed relevant measurements and prepare a revised text according to your suggestion. The main changes are as follows: 1) The title of manuscript "Single crystal-to-single crystal and spin-crossover transformations via phasecoexistence state in pore-adjustable frameworks" has been changed into "A spin-crossover framework endowed with pore-adjustable behavior by slow structural dynamics".
3) The programmable sorption has been explained as "slow lcp-nqp dynamics" and "a pore rearrangement associated with simultaneous pore opening and closing". The Conclusion section has also been modified, as shown below marked in yellow: The simultaneous pore opening and closing involved in the pore rearrangement leads to slow nqp-lcp dynamics, where nqp phase need to long-time exposure in saturated steam to accomplish the nqp-to-lcp gate-opening adsorption.
Moreover, the structural transformation of the magnetic framework shifts the SCO properties of the Fe II magnetic centers. This study presents an unprecedent adsorption-related pore transformation accompanied by activation-method dependent adsorption. Such an exotic property can be used in intelligently adjustable gas adsorption, actuation, and sensing. [lines [1][2][3][4][5][6]Page 11] In the section of Introduction, the sentence "Therefore, the intercorrelation between the guests and SCO frameworks potentially leads to intriguing magnetic switching that directly entangles the local and global structural transformations involved in guest adsorption." has been changed into "Therefore, the Additional comments: 11. "the decomposition of framework of 1 should be precluded, as we can re-obtained the crystal structure of 1·4/3H2O by exposing one of the above single crystals in the air" [rebuttal, page 11]. The ability to reobtain the crystalline form by re-solvation does not confirm the stability of the parent framework.

Response:
The sentences "Notably, the PXRD pattern after the measurement was same with that before adsorption experiments, suggesting the robust crystal lattice of this sample ( Supplementary Fig. 11)" have been changed into "Notably, the PXRD pattern after two isothermal vapor ad/de-sorption or the adsorptiondesorption-cycles measurement revealed that the crystallinity and framework of nqp and lcp structure type samples can both be revived by rehydration (Supplementary Fig. 11)." [line 26 in Page 5 and lines 1-2 in Page 6].
12. Supporting Fig. 11 -it would be more appropriate to compare the sample after sorption experiments with the already activated sample (Supp. Fig. S11A -I believe that PXRD pattern from Supp. Fig. S8 may be used for that).
Response: Supplementary Fig. 11 has been modified according to your suggestion:

Supplementary Fig. 11 PXRD patterns of samples after in situ activation (Blue) and after two adsorption isotherm experiments and the continuous adsorption-desorption-cycles measurement (Green). A, The
PXRD pattern of sample after two isothermal vapor ad/de-sorption (in the Fig. 2A  13. On several occasions experimental patterns were compared to the simulated pattern for 1.4/3H2O at 100 K (for example Supp. Fig. S13) -please replace it with the simulated pattern for structure at 250 K.

Response:
The simulated pattern for 1·4/3H2O has been replaced with that for structure at 250 K in Supplementary Fig. 8, 12-14. 14. Fig. 2B -"activation" arrow should end around 1300 minutes. The caption for Supplementary Fig. 10 has also been modified: Supplementary Fig. 10  15. Article, page 14 -in the description of Raman setup milimeters should probably be replaced with micrometers.

Response:
The Raman setup in this work was also used in elsewhere (Chemosphere, 2020, 241, 124960).
We have re-checked and modified the parameters of the Raman setup as blow: Laser beam was focused on the selected region of single crystal through a 50 × objective lens (0.75 numerical aperture), which provided spatial resolution of about 6 m. [lines 22-23, page 13] Response to reviewer #2: Comments to Authors: Many of reviewer 1's comments on the original manuscript, and some of mine, concerned the crystallography.
That has been addressed by remeasuring or re-refining all the structures in the study, including some new data collections with synchrotron radiation. The new structural data are a significant improvement on the originals, and the many of the experimental issues itemised by reviewer 1 have now been addressed. The new crystal structures from the nqp phase are of reasonable quality, for the product of a single-crystal-tosingle-crystal annealing reaction.
The revision also includes new thermogravimetric analyses and extra magnetic data (which I requested), and single crystal Raman microscopy (to address a comment by reviewer 1). Those are all helpful additions.
I have just a few new comments to address before final acceptance of the manuscript.

Response:
We thank the reviewer for positive comments on our work and valuable suggestions concerning the manuscript.
1. My only criticism of the new data, is that the Raman microscopy data in Supplementary Figure 23 don't clearly show the co-existence of both phases in the same crystal, as proposed in the caption. Spectra E-H all look the same; I-L all look the same; and M-P all look the same. So, the phase composition at all four points of the crystal looks the same, under each of the conditions measured. So, that experiment was worth doing, but it doesn't prove the two phases can co-exist in the same crystal, at the same time.
At best, what it shows is that the domains of the two phases in the mixed-phase crystal must be smaller than the resolution of the Raman microscope. The caption to Supplementary Figure 23, and the description on lines 167-175, should be changed to reflect that. Supplementary Figure 19 does show the two phases can co-exist in the same crystal, though, so that conclusion is sound on a macroscopic level, even if it was not observed microscopically.
Response: According to your suggestion, we have re-analyzed the Raman spectrum in details and the related sentences in the manuscript have been revised.
Lines 24-27 in page 6 and lines 1-7 in page 7: In order to further verify that the activation-method dependent adsorption properties are related to structural difference between nqp and partially dehydrated frameworks, micro-Raman spectra experiments (spot diameter ~2 m) were performed on single crystals 56,57 .
As shown in Supplementary Fig. 19 in the micro-Raman spectra verify the structural dependent water adsorption property in this material.
In addition, Supplementary Fig. 19 and 20 (caption) have also been modified.